Sonja Farak, of Northampton, was charged with possession of heroin and cocaine.

Farak, who works at a lab in Amherst, is also accused of removing and tempering with and removing drug evidence from the lab.

According to court documents, Farak's supervisor found: "In a sandwich bag was a substance that appeared to be crack cocaine."

The substance tested positive for cocaine.

Police also found drugs in Farak's Volkswagen Golf, according to court documents.

"Numerous items of packaging used by the drug lab to store analyzed controlled substances were located throughout the vehicle," according to court documents. "In a storage bin inside the driver's door, a clear plastic baggie containing a white powder that appeared to be cocaine, and a brownish substance, consistent with a substance laced with heroin, was located."

Farak was ordered held on $5,000 bail.

Attorney General Martha Coakley said it was not believed Farak's tampering will undermine evidence or cases.

Last month, the other chemist, Annie Dookhan, was indicted on 27 charges in a case that threatens to unravel thousands of drug convictions. Dookhan, of Franklin, resigned in March during an internal investigation by the state Department of Public Health. She has pleaded not guilty.

State police said they closed the Boston lab where she worked in August after taking over its operation and discovering the extent of her misconduct.

The accusations against Farak, unlike those against Dookhan, don't involve falsification of tests or dry labbing, visually identifying samples instead of performing required chemical testing, the attorney general said.

The Amherst lab has been closed temporarily, and chemists will be transferred to Sudbury, state police said.

Lawyers for Boston Marathon bomber Dzkokhar Tsarnaev rested their case in his federal death penalty trial Tuesday after presenting a brief case aimed at showing his late older brother was the mastermind of the 2013 terror attack.